Project Summary Human health and well-being hinges on frequent and meaningful social contact with other humans, which is satisfied by establishing close social relationships (Baumeister & Leary, 1995). Indeed, independent of the frequency of social contact, perceptions of social connectedness predict well-being (Holt-Lunstad, Smith, Baker, Harris, & Stephenson, 2015), suggesting that the psychological distance between one's self and close others reflect important individual difference measures that are not, as of yet, objectively measurable. To better gauge this psychological representation of relationship closeness, the proposed research turns to multivariate neuroimaging techniques capable of parsing the representational content reflected in patterns of brain activation. A region of the medial prefrontal cortex (MPFC) consistently and robustly activates when making judgments related to the self relative to judgments of others, though it occasionally activates moderately in response to judgments of close others. This proposal takes a more fine-grained approach to understanding the relationship between relational closeness and MPFC activation by modeling the activation patterns associated with the self and a gradation of close others. In doing so, we will determine if relationship closeness is represented in the similarity of neural activation patterns to judgments of the self and of close others (Aim 1). Moreover, by analyzing the similarity of neural activation patterns elicited by making trait judgments for one's self and close others, we aim to determine how the structure of self-representation might reflect social well- being (Aim 2). That is, is the neural representation of the self more dissimilar from close others in lonely individuals than in well-connected individuals? In sum, the present proposal applies a novel computational neuroimaging technique to the psychological construct of self-representation to determine if self-representation is instantiated in neural patterns of activation; and further, if the structure associated with such representation is 1) inclusive of close others and 2) sensitive to cognitive distortions (e.g., perceived social disconnectedness) and thus diagnostic of psychological well-being.